This invention relates to a bushing or feeder, for processing molten glass of the kind having a bottom wall for delivering streams of molten glass for attenuation into fibres and side walls and end walls extending upwardly from the bottom wall, terminal means being provided on each end wall for connecting electrical energy to the feeder to heat said walls. The invention also includes a method of making a bushing of the kind referred to above.
The invention more particularly relates to an improvement or modification of a bushing or feeder of the type described in U.K. patent specification No. 1,215,743 in the name of Owens-Corning Fiberglas. That specification describes various designs of lugs or terminal means designed to afford an area to which a terminal clamp connecting the lug to a bus-bar can be affixed. As indicated in that specification, in order to achieve a uniform distribution of current density across the end walls, it is necessary to design the lugs to achieve a line of equipotential extending across the end wall substantially parallel with a line defined by the junction of the bottom and end walls. Each terminal means has an outer portion to receive an electrical connection and an inner portion including at least two elements providing spaced contact on the end wall.
In constructing a bushing end wall complete with terminal means, as at present practised, it is necessary to fabricate each assembly from the individual parts, and then weld those parts together to form the assembly. That process, apart from involving a considerable amount of cutting of metal pieces from sheets of different thickness with consequent loss of metal, can introduce a variable resistance in the wall end leading to poor running of the bushing. We have now found that by forming the complete assembly by a lost was casting process, we can attain the following benefits:
1. A reduction in the time taken to construct a bushing.
2. A considerable reduction in metal loss during manufacture, and the amount of valuable metal carried in stock.
3. The possibility of consistent manufacture in terms of actual dimensions and electrical characteristics.
4. As a result of more consistent and better electrical characteristics, a better bushing in terms of manufacturing performance, and ease of running during the normal life of the bushing.
5. Reduce the actual weight of metal used in the terminal and wall together.